Tube mill and process



Feb. 15 1927.

O. BAMBERGER TUBE MILL AND PROCESS Filed April 6, 1925 )NVE/vrai? wlw@ Patched Feb. 15,192.1.'

OTERO BmEMER, 0l' DUISBURG, GEBIAN'Y.

TUBE lum. AND raocnss'.

Application :lled April 6, 1925. Serial No. 21,159.

This invention comprehends improvements in the seamless metal tube making art and has for an object the production of tubes by the so-called pilgrim process of much more uniform and exact dimensions than has before been possible by this process.

As heretofore practiced the pilgrim process consisted essentially in heating round ingots in a furnace, piercing, rolling into tubes in the pilgrim mill and sawing the tubes to the desired length, additional steps of sizing, straightening and cooling being performed if further refinements were required. This process has many marked advantages over such processes as the so-called automatic mill process in which the tube, instead of being subjected to the action of a pilgrim mill after the piercing operation, `is subjected to the action of a set of rolls on a plurality of mandrels of increasing size in succession which enlarge the internal diameter of the tube and decrease the thickness of its wall. -In the automatic mill process it is necessary, for instance, to employ very high grade material which has to be specially worked through a succession of steps before it can be sulijected to the piercing and enlarging operations, requiring the services of many employees, whereas in the pilgrim process round cast ingots are used and the entire operation is substantially automatic. Moreover, by the so-called automatic mill process tubes cannot conveniently be made more than 24. feet in length, whereas by the ilgrim mill process they may be made eet or longer with the resulting advantage in the latter case that if sawed-say into 20 foot lengths, the waste at the two ends is divided between the three pipe lengths, where as in the automatic mill the entire waste at both ends falls upon one pipe length. These and other advantages inherent in the pilgrim mill process, which will be obvious to those skilled in the art, render its use economically highly desirable and for most purposes, as in making pipes for sewers and ordinary pipe lines, the process as heretofore de scribed is sufficient.

However, the rolls of the pilgrim mill may become worn, or for other reasons give rise to irregularities on the outer surface of the tube, although its inner surface may be perfectly smoot 1 due to the action of the mandrel. When such a tube is passed to the sizing mill the irregularities on the outer surface are pressed through te the inner face which in turn becomes uneven. If it be attempted to employ a mandrel in the siz ing mill the material will be forced between the pcripheries of the sizing rolls resulting 1n ridges on the outer surface. It results that these tubes frequentlyfail to meet certain exacting requirements such as those of oil field work and it is the purpose of my present invention to overcome this diiliculty. This, I prefer to accomplish by reheating the tube after it leaves the pilgrim mill and subjecting it to the action of a polishing mill, comprising an inner mandrel with enlarged head and outer rolls. This mill imparts to the tube substantially smooth inside and outside surfaces with uniform thickness of wall and uniform inside and outside diameters. Thereafter the sizing mill fixes the exact diameter of the tubes without modifying the symmetrical arrangement of the inner and outer surfaces.

The invention has for a further object the arrangement of a set of reducing mills in effective parallelism to the set of polishing, sizing and straightening mills whereby the same initial tube forming mechanism, reheating furnace and conveyor mechanism may be employed for supplying tubes to the respectiy'e sets. The polishing set will ordinarily take from the pilgrim mill the tubes of larger diameter, for instance, 6 inches and above, While the reducing mills will ordinarily take the smaller tubes, for instance, those less than 6 inches,`and reduce them to still smaller sizes. Y

This arrangement aiords great flexibility of operation since it makes it possible to sub-v ject the larger tubes from the pilgrim mill to a polishing, sizing and straightening operation, or-if the polishing mill is released from duty-to a simple sizing and straightening operation without polishing, while small tubes from the same pilgrim mill may be subjected to a succession of oprations in the reducing mills of the number essential to reduce them to the sizes desired.

In addition to the eneral objects recited above, the invention 12'has for other objects such other improvements or advantages in construction and operation as are found to obtain in the structures and processes hereinafter described or claimed.

ln the accompanying drawings, forming a part of the specification, and showing, for purposes .of exemplllication a preferred form and` nianp W.'

eh the eventien may ba embodied and practiced, but without limiting the claimed invention specifically to such illustrative instance or instances: y

Figure 1 of the drawin is a diagrammatic view of a tube plant o the pilgrim mill type'embodying the Special features of my invention, comprising a polishing mill between the reheating furnace and the sizing mill, and reducing mills in parallel thereto; Fig. 2 is an enlarged diagrammatic figure partly in section of the polishing mill.

Referring to the drawings there are shown a heating furnace 1 in which round cast ingots are heated; a piercing mill 2 for iercing the hot ingots, and associated housing 3 and bearing 4; means 5 for transferring the ingots from the furnace to the piercing mill; and carriage 6 for conveying the ierced ingots to the pilgrim mill 7, which atter comprises the usual pilgrim rolls 8;y

roll rotating mechanism 9 and mandrel operating mechanism 10. .Here the pierced ingots are all forged into tubes. From the pilgrim mill the tubes are led to the saws 11 by which they are cut into approprzate lengths. These tubes are now suitable for certain purposes` but if further refinements are desired they are then assed by the transfer table 12 and roll tab e 13 to the reheating furnace 14 where their temperature is raised to the point required for further successful treatment-say in the neighborhood of 900 or 950 C. The larger tubes are led by the conveyor mechanism 15 from the reheating furnace 14 to the polishing, sizing and straightening set of mechanism, whereas the smaller tubes are led by the same conveyor mechanism 15 to the set of reducing mills in parallel to the former set.

The polishing mill consists of two positively rotated rolls 16 having their axes slightly skewed with reference to each other, and a rod 17 with attached mandrel head 18 located, when in advanced or operative position, between the rolls. Here the tube is ushed over the mandrel head between the po ishing rolls and is fed forward and rotated over said mandrel head by the drivin action of the rolls. By this method the tu e receives an inner and outer polished surface and its walls are rendered of uniform thickness, and as a. consequence also its internal and external diameters will be `uniform. When the olishing process is completed the rod and) mandrel are pulled out of the tube, the tube is thrown sideways a'nd led b. transfer means 19 to the sizing mill 20, o known construction, comprising two rolls with' parallel axes, each roll being provided circumferentially with semi-circular grooves, the peripheries of the rolls meeting to form a circular passageway of pre-determined diameter for the passage ofthe tubes. In this mill the tube is rolled to the proper voutside diameter, thev internal surface, be-

cause of the uniform thickness of the wall imparted by the polishing machine,'pre

`serving its symmetrical relation relative to the outer surface. Then the warm tube is passed by the conveyor 21 to the straight ening machine 22 where -it is straightened for its'full length and is finally, brought to the cooling bed 23. Tubes thus made meet the most exacting requirements.

The smaller tubes from the pilgering mill are passed from the reheating furnace 14, by the conveyor 15, to the reducin mill 30, of known construction, provide with the rollers 31, driven by motor 3.11, which successively reduce their diameter, and from this mill the tubes may be led to the cooling rack 32, and if they are to be still further reduced in diameter, to a second reducing mill 33 of similar construction and from thence they are passed tothe cooling rack-34.

It is thus apparent that in accordance with my invention tubes of a variety of characteristics may be produced by a single plant. Thus tubes as they issue from the pilgrim mill may without further treatment be suitable for sewers, ordinary pipe lines, or similar purposes, while those required for special. urposes can be further treated after 'they issue from the pilgrim mill Ain a variety of ways according to the characteristics which it is desired to impart thereto. For instance-the larger tubes may be subjected to the polishing and sizing operation, or, if desired, the polishing operation may be omitted and the tube passed directly to the sizing and straightening machines, while smallertubes may be passed from the re- 'heating furnace directly to the first redlicing mill where they are reduced in diameter, and if further reduction is desired, to the second reducing mill.

There results not only a material saving in installation costs but also a material saving in operation costs since it is possible for a single operator to oversee the various operations.

The invention as hereinabove set forth is embodied in a particular form of construction but may be variously embodied within the scope of the claims hereinafter made.

I claim:

1. The improvement in the process of making tubes by heating round ingots, punching, roll forging, reheating and sizing, and similar processes, which improvement comprises the step of rotating said tubes around and along a polishing device and between feeding and polishing rolls whereby smooth concentric inner and outer cylindrical surfaces of substantially uniform diameters are imparted to said tubes, said step being performed between the reheating and sizing operations; substantially as specified.

2. The improvement in the process of making tubes by heating round ingots,

Utl

punchin and roll forging, and similar processes, w ich improvement comprises rotating said tubes after they leave the forging operation around and along a mandrel head whereby the interior surfaces of said tubes are rendered smooth and reduced to substantially uniform diameter; substantially as specified.

3. The process of treating tubes produced by the pilgrim or similar method, which process comprises passing said tubes from the pilgrim mill to a reheating device and reheating said tubes thereby; and rotating them while in the reheated condition around a polishing device to impart smooth inner cylindrical surfaces of substantially uniform diameters thereto; substantially as specified.

4. The process of im arting substantially exact dimensions to tu es produced by the pilgrim or similar method, which process comprises reheating said tubes after they have been formed by said method andsubjecting them while in the reheated condition to the action of external and internal rubbing instrumentalities, said tubes and in strumentalities having relative circumferential motion with respect to each other, whereby the walls of said tubes are reduced to substantially uniform thickness and smoothness; substantially as s ecified.

5. The rocess of treating tu es produced by the pllgrim or similar method, which process comprises subjecting said tubes after they have left the pilgrim mill to the action of external and internal frictional polishing instrumentalities, said tubes and instrumentalities having relative circumferential and longitudinal motion with 4respect to each other, whereby the walls of said tubes are reduced to substantially uniform thickness and smoothness; substantially as specified.

6. The process of treating tubes formed by the pilgrim or similar method, which process comprises subjecting said tubes to f the action of an internal frietional polishing instrumentality, said tubes and instrumentality having relative circumferential motion with respect to each other, wherebythe inner surfaces are rendered smooth and of substantially 'uniform diameters; substantially as specified.

7. In a tube makin system in combination: means for punc ling and forgin ingots into completed tubes; and polis ing means having circumferential movements pleted tubes therefrom comprising polishing means having circumferential movements relative to the exterior and interior surfaces of said tubes to impart thereto smooth external and internal surfaces, respectively; a second set of devices including a series of reducing mills in parallel to said first set;

whereby the tubes may be directly transferred from said reheating furnace to said first set of devices or, electively, to said second set of devices; substantially as specified.

9. A tube mill system comprising a pilgrim mill; a set of devices 1n series with said mill for refinishing the completed tubes therefrom comprising polishing means having circumferential movements relative to the exterior and interior surfaces of said tubes to impart thereto smooth external and internal surfaces, respectively; a second set of devices including a series of reducing mills in parallel to said first set; whereby the tubes mayv be transferred from the pilgrim mill to said first set of devices, o1 electively, to said second set of devices, substantially as specified.

10. A. tube mill system comprising a pilgrim mill; a set of devices in series with said mill for` refinishing the completed tubes therefrom comprising sizing and straightening devices; a second set of devices includin a series of reducing mills in parallel to sai first set; whereby the tubes may be transferred from the pilgrim mill to said first st o f devices or, electively, to said second set of devices; substantially as s'ecified.

In testimony whereof, I ave hereunto set 

